Question: What is the greatest common factor of $20$ and $16$ ? Another way to say this is: $\operatorname{gcf}(20, 16) = {?}$
Explanation: The greatest common factor is the largest number that is a factor of both $20$ and $16$ The factors of $20$ are $1$ $2$ $4$ $5$ $10$ , and $20$ The factors of $16$ are $1$ $2$ $4$ $8$ , and $16$ Thus, the greatest common factor of $20$ and $16$ is $4$. $\operatorname{gcf}(20, 16) = 4$